Heat exchanger and oxygenator

ABSTRACT

A heat exchanger for a blood circulation circuit comprises a hollow fiber membrane layer having a plurality of hollow fiber membranes, and a fixing portion fixing both end portions of the hollow fiber membranes from outsides of the hollow fiber membranes. The fixing portion mainly contains polyurethane, and each of the hollow fiber membranes has a heat conductive layer containing high density polyethylene, and an adhesion layer provided on an outside of the heat conductive layer, bonded to the fixing portion, and mainly containing a modified polyolefin resin.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT Application No.PCT/JP2018/001371, filed Jan. 18, 2018, based on and claiming priorityto Japanese Application No. 2017-012542, filed Jan. 26, 2017, both ofwhich are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a heat exchanger and an oxygenator.

In the related art, a heat exchanger and an oxygenator having a hollowfiber membrane layer which is constituted of a large number of hollowfiber membranes and which has a cylindrical shape as a whole are known.In this hollow fiber membrane layer having a cylindrical shape, a hollowfiber membrane sheet as disclosed in U.S. Pat. No. 4,911,846 can beapplied. In U.S. Pat. No. 4,911,846, a large number of hollow fibermembranes are disposed substantially in parallel so as to be weftstrings, and these are woven together with warp strings, thereby forminga bamboo blind-shaped sheet. Such a bamboo blind-shaped hollow fibermembrane sheet can be folded to form a hollow fiber membrane layerhaving a prismatic outer shape, or a hollow fiber membrane layer havinga columnar shape. Such a hollow fiber membrane layer is housed in ahousing, and both end portions thereof are fixed to the housing throughthe partition walls (fixing portions).

In clinical settings using an oxygenator, in order to reduce the burdenon patients, it is required to reduce the total volume of a gap betweenthe hollow fiber membranes, that is, the blood filling amount. In orderto reduce blood filling amount of the hollow fiber membrane layer whilemaintaining the heat exchange performance, it is conceivable to use amaterial having a high thermal conductivity.

However, in the case of using high density polyethylene which is a resinmaterial having a high thermal conductivity, the adhesion between thehollow fiber membrane layer and the partition wall is not sufficient, sothat the hollow fiber membrane layer and the partition wall may beseparated. There is a concern that a heat medium (water or hot water)passing through the inside of each of the hollow fiber membranes mayflow out to the outside of the hollow fiber membranes and be mixed intothe patient's blood due to this separation.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a heat exchanger and anoxygenator capable of reducing filling amount of a liquid (such asblood) to be subjected to heat exchange in the heat exchanger andcapable of enhancing the adhesion between a hollow fiber membrane layerand a fixing portion.

A heat exchanger for achieving the above object comprises a hollow fibermembrane layer having a plurality of hollow fiber membranes, and afixing portion fixing both end portions of the hollow fiber membranesfrom outsides of the hollow fiber membranes, in which the fixing portionmainly contains polyurethane, and each of the hollow fiber membranes hasa heat conductive layer containing high density polyethylene, and anadhesion layer provided on an outside of the heat conductive layer,bonded to the fixing portion, and mainly containing a modifiedpolyolefin resin.

The heat exchanger may further comprise a barrier layer provided on theoutside of the heat conductive layer and on an inside of the adhesionlayer and having a barrier property with respect to hydrogen peroxide.

The adhesion layer may preferably contain modified polyethylene.

The barrier layer preferably mainly contains a crystalline resinmaterial.

The heat conductive layer preferably has a thermal conductivity of 0.3W/m·K or higher and 0.6 W/m·K or lower.

The hollow fiber membrane preferably has an outer diameter of 1 mm orless.

The hollow fiber membrane layer preferably has a shape of a cylindricalbody and has the hollow fiber membranes wound around a central axis ofthe cylindrical body and inclined with respect to the central axis ofthe cylindrical body.

The hollow fiber membrane layer preferably has a shape of a cylindricalbody, and has warp strings in which the hollow fiber membranes aredisposed along a central axis of the cylindrical body and weft stringsin which the hollow fiber membranes are disposed in a directionintersecting with the central axis of the cylindrical body, and the warpstrings and the weft strings are braided.

According to the present invention, it is possible to enhance adhesionbetween the adhesion layer on the outermost layer of the hollow fibermembranes and the fixing portion. Accordingly, it is possible to preventthe hollow fiber membrane layer from being separated from the fixingportion, and to prevent the heat medium (water or hot water) passingthrough the inside of each of the hollow fiber membranes from flowingout to the outside of the hollow fiber membranes and being mixed intothe patient's blood.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an oxygenator comprising a heat exchanger(first embodiment) of the present invention.

FIG. 2 is a view of the oxygenator shown in FIG. 1 when seen from adirection of arrow A.

FIG. 3 is a cross-sectional view taken along line B-B in FIG. 2.

FIG. 4 is a view when seen from a direction of arrow C in FIG. 2.

FIG. 5 is a cross-sectional view taken along line D-D in FIG. 1.

FIG. 6 is a cross-sectional view taken along line E-E in FIG. 5.

FIG. 7A is a perspective view, and FIG. 7B is a development view showinga process of manufacturing a hollow fiber membrane layer provided in theoxygenator shown in FIG. 1.

FIG. 8A is a perspective view, and FIG. 8B is a development view showingthe process of manufacturing the hollow fiber membrane layer provided inthe oxygenator shown in FIG. 1.

FIG. 9 is a transverse view of a hollow fiber membrane provided in thehollow fiber membrane layer shown in FIG. 1.

FIG. 10 is a plan view showing a hollow fiber membrane sheet beforebecoming a hollow fiber membrane layer of a heat exchanger (secondembodiment) of the present invention.

FIG. 11 is a perspective view of a hollow fiber membrane layer formed byfolding the hollow fiber membrane sheet shown in FIG. 10.

FIG. 12 is a perspective view of a hollow fiber membrane layer providedin a heat exchanger (third embodiment) of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, a heat exchanger and an oxygenator according to the presentinvention will be described in detail based on preferred embodimentsshown in accompanying drawings.

First Embodiment

FIG. 1 is a plan view of an oxygenator comprising a heat exchangeraccording to the present invention (first embodiment) . FIG. 2 is a viewof the oxygenator shown in FIG. 1 when seen from a direction of arrow A.FIG. 3 is a cross-sectional view taken along line B-B in FIG. 2. FIG. 4is a view when seen from a direction of arrow C in FIG. 2. FIG. 5 is across-sectional view taken along line D-D in FIG. 1. FIG. 6 is across-sectional view taken along line E-E in FIG. 5. FIG. 7A is aperspective view, and FIG. 7B is a development view showing a process ofmanufacturing a hollow fiber membrane layer provided in the oxygenatorshown in FIG. 1. FIG. 8A is a perspective view, and FIG. 8B is adevelopment view showing the process of manufacturing the hollow fibermembrane layer provided in the oxygenator shown in FIG. 1. FIG. 9 is atransverse view of a hollow fiber membrane provided in the hollow fibermembrane layer shown in FIG. 1.

Note that, in FIGS. 1, 3, 4, and 7 to 9, the left side is referred to as“left” or a “left portion (one side)” and the right side is referred toas “right” or a “right portion (the other side)”. In addition, in FIGS.1 to 6, the inside of the oxygenator will be described as a “bloodinflow side” or an “upstream side” and the outside will be described asa “blood outflow side” or a “downstream side”.

The entire shape of an oxygenator 10 shown in FIGS. 1 to 5 is in asubstantially columnar shape. This oxygenator 10 is a heatexchanger-attached oxygenator comprising: a heat exchange portion 10Bwhich is provided inside the oxygenator and performs heat exchange onblood; and an oxygenator portion 10A which is provided on an outerperipheral side of the heat exchange portion 10B and is used as a gasexchange portion performing gas exchange on blood. The oxygenator 10 isinstalled, for example, in an extracorporeal blood circulation circuit.

The oxygenator 10 has a housing 2A in which the oxygenator portion 10Aand the heat exchange portion (heat exchanger) 10B are housed.

The housing 2A comprises: a cylindrical housing main body 21A; adish-like first lid body 22A which seals a left end opening of thecylindrical housing main body 21A; and a dish-like second lid body 23Awhich seals a right end opening of the cylindrical housing main body21A.

The cylindrical housing main body 21A, the first lid body 22A, and thesecond lid body 23A are formed of a resin material. The first lid body22A and the second lid body 23A are fixed to the cylindrical housingmain body 21A through a method such as welding or adhesion using anadhesive.

A tubular blood outlet port 28 is formed on the outer peripheral portionof the cylindrical housing main body 21A. This blood outlet port 28protrudes toward a substantially tangential direction of the outerperipheral surface of the cylindrical housing main body 21A (refer toFIG. 5).

A tubular purge port 205 is protrusively formed on the outer peripheralportion of the cylindrical housing main body 21A. The purge port 205 isformed on the outer peripheral portion of the cylindrical housing mainbody 21A such that a central axis of the purge port 205 intersects witha central axis of the cylindrical housing main body 21A.

A tubular gas outlet port 27 is protrusively formed on the first lidbody 22A. The gas outlet port 27 is formed on the outer peripheralportion of the first lid body 22A such that a central axis of the firstlid body intersects with the center of the first lid body 22A (refer toFIG. 2).

In addition, a blood inlet port 201 protrudes from an end surface of thefirst lid body 22A such that a central axis of the blood inlet port iseccentric to the center of the first lid body 22A.

A tubular gas inlet port 26, a heat medium inlet port 202, and a heatmedium outlet port 203 are protrusively formed on the second lid body23A. The gas inlet port 26 is formed at an edge portion of the endsurface of the second lid body 23A. The heat medium inlet port 202 andthe heat medium outlet port 203 are formed at a substantially centralportion of the end surface of the second lid body 23A. In addition,central lines of the heat medium inlet port 202 and the heat mediumoutlet port 203 are slightly inclined to a central line of the secondlid body 23A.

Note that, in the present invention, the entire shape of the housing 2Adoes not necessarily have a complete columnar shape, and may have, forexample, a partially missing shape or a shape to which an irregularportion is added.

As shown in FIGS. 3 and 5, the oxygenator portion 10A having acylindrical shape along the inner peripheral surface of the housing 2Ais housed inside the housing 2A. The oxygenator portion 10A comprises: acylindrical hollow fiber membrane layer 3A; and a filter member 41A usedas air bubble removing means 4A provided on the outer peripheral side ofthe hollow fiber membrane layer 3A. The hollow fiber membrane layer 3Aand the filter member 41A are disposed in order of the hollow fibermembrane layer 3A and the filter member 41A from a blood inflow side.

In addition, the cylindrical heat exchange portion 10B is providedinside the oxygenator portion 10A and disposed along the innerperipheral surface of the oxygenator portion 10A. The heat exchangeportion 10B has the cylindrical hollow fiber membrane layer 3B.

As shown in FIG. 6, each of the hollow fiber membrane layers 3A and 3Bcomprises a plurality of hollow fiber membranes 31, which are laminatedin layers. For example, the number of layers laminated is preferably,but not limited to, 3 to 40. Note that each of the hollow fibermembranes 31 in the hollow fiber membrane layer 3A has a gas exchangefunction. On the other hand, each of the hollow fiber membranes 31 inthe hollow fiber membrane layer 3B has a heat exchange function ofperforming heat exchange.

As shown in FIG. 3, both end portions of the hollow fiber membranelayers 3A and 3B are collectively fixed to the inner surface of thecylindrical housing main body 21A using partition walls 8 and 9. Thepartition walls 8 and 9 mainly contain polyurethane.

Furthermore, the inner peripheral portion of the hollow fiber membranelayer 3B is engaged with an irregular portion 244 formed on the outerperipheral portion of a first cylindrical member 241. The hollow fibermembrane layer 3B is reliably fixed to the cylindrical housing main body21A through fixation using the partition walls 8 and 9 and thisengagement. Accordingly, it is possible to reliably prevent positionaldeviation of the hollow fiber membrane layer 3B from occurring duringuse of the oxygenator 10. In addition, the irregular portion 244 alsofunctions as a flow path for circulating blood B throughout the hollowfiber membrane layer 3B.

Note that, as shown in FIG. 5, the maximum outer diameter ϕD1 _(max) ofthe hollow fiber membrane layer 3A is preferably 20 mm to 200 mm, andmore preferably 40 mm to 150 mm. The maximum outer diameter ϕD2 _(max)of the hollow fiber membrane layer 3B is preferably 10 mm to 150 mm, andmore preferably 20 mm to 100 mm. In addition, as shown in FIG. 3, alength L of the hollow fiber membrane layers 3A and 3A along a centralaxis direction is preferably 30 mm to 250 mm, and more preferably 50 mmto 200 mm. With such conditions, the hollow fiber membrane layer 3A hasan excellent gas exchange function and the hollow fiber membrane layer3B has an excellent heat exchange function.

A blood flow path 33 through which the blood B flows from the upper sideto the lower side in FIG. 6 is formed on the outside of each of thehollow fiber membranes 31 between the partition wall 8 and the partitionwall 9 in the housing 2A, that is, in a gap between the hollow fibermembranes 31.

A blood inflow side space 24A communicating with the blood inlet port201 is formed upstream of the blood flow path 33 as a blood inletportion of the blood B flowing in from the blood inlet port 201 (referto FIGS. 3 and 5).

The blood inflow side space 24A is a space defined by the firstcylindrical member 241 forming a cylindrical shape and a plate piece 242which is disposed inside the first cylindrical member 241 and isdisposed so as to face apart of the inner peripheral portion of thefirst cylindrical member. The blood B flowing in the blood inflow sidespace 24A can flow down throughout blood flow paths 33 through aplurality of side holes 243 formed in the first cylindrical member 241.

In addition, a second cylindrical member 245 concentrically disposedwith the first cylindrical member 241 is disposed inside the firstcylindrical member 241. As shown in FIG. 3, a heat medium H, forexample, water, flowing in from the heat medium inlet port 202 isdischarged from the heat medium outlet port 203 after passing through aflow path (hollow portion) 32 in each of the hollow fiber membranes 31of the hollow fiber membrane layer 3B on the outer peripheral side ofthe first cylindrical member 241, and the inside of the secondcylindrical member 245 in order. In addition, heat exchange (heating orcooling) is performed between the blood B coming into contact with thehollow fiber membranes 31 in the blood flow paths 33 and the heat mediumH when the heat medium H passes through the flow path 32 of each of thehollow fiber membranes 31.

The filter member 41A having a function of capturing air bubblesexisting in the blood B flowing through the blood flow paths 33 isdisposed downstream of the blood flow paths 33.

The filter member 41A is formed of a sheet-like member having asubstantially rectangular shape (hereinafter, simply referred to as a“sheet”), and is formed by winding the sheet along the outer peripheryof the hollow fiber membrane layer 3A. Both end portions of the filtermember 41A are also fixed using the partition walls 8 and 9, and thus,are fixed to the housing 2A (refer to FIG. 3). Note that, it ispreferable that the inner peripheral surface of the filter member 41A isprovided in contact with the outer peripheral surface of the hollowfiber membrane layer 3A, and covers substantially the entire outerperipheral surface.

In addition, even if there are air bubbles in blood flowing through theblood flow paths 33, the filter member 41A can capture the air bubbles(refer to FIG. 6). In addition, air bubbles captured by the filtermember 41A are pushed into each of the hollow fiber membranes 31 in thevicinity of the filter member 41A by blood. As a result, the air bubblesare removed from the blood flow paths 33.

In addition, a cylindrical gap is formed between the outer peripheralsurface of the filter member 41A and the inner peripheral surface of thecylindrical housing main body 21A and forms a blood outflow side space25A. A blood outlet portion is formed by this blood outflow side space25A and the blood outlet port 28 communicating with the blood outflowside space 25A. When the blood outlet portion has the blood outflow sidespace 25A, a space through which the blood B that has been transmittedthrough the filter member 41A flows toward the blood outlet port 28 issecured, and therefore, it is possible to smoothly discharge the bloodB.

As shown in FIG. 3, an annular rib 291 is protrusively formed inside thefirst lid body 22A. A first chamber 221 a is defined by the first lidbody 22A, the rib 291, and the partition wall 8. This first chamber 221a is a gas outlet chamber through which gas G flows out. The left endopening of each of the hollow fiber membranes 31 of the hollow fibermembrane layer 3A opens to and communicates with the first chamber 221a. In the oxygenator 10, a gas outlet portion is formed by the gasoutlet port 27 and the first chamber 221 a. On the other hand, anannular rib 292 is also protrusively formed inside the second lid body23A. A second chamber 231 a is defined by the second lid body 23A, therib 292, and the partition wall 9. This second chamber 231a is a gasinlet chamber through which gas G flows in. The right end opening ofeach of the hollow fiber membranes 31 of the hollow fiber membrane layer3A opens to and communicates with the second chamber 231 a. In theoxygenator 10, a gas inlet portion is formed by the gas inlet port 26and the second chamber 231 a.

Here, the flow of the blood in the oxygenator 10 of the presentembodiment will be described. In this oxygenator 10, the blood B flowingin from the blood inlet port 201 flows into the heat exchange portion10B after passing through the blood inflow side space 24A and the sideholes 243 in order. In the heat exchange portion 10B, heat exchange(heating or cooling) is performed such that the blood B comes intocontact with the surface of each of the hollow fiber membranes 31 of theheat exchange portion 10B while flowing through the blood flow paths 33in a downstream direction. The blood B which has been subjected to heatexchange in this manner flows into the oxygenator portion 10A.

In the oxygenator portion 10A, the blood B flows through the blood flowpaths 33 in a further downstream direction. On the other hand, gas (gascontaining oxygen) supplied from the gas inlet port 26 is distributedfrom the second chamber 231 a into the flow paths 32 of the hollow fibermembranes 31 of the oxygenator portion 10A, accumulated in the firstchamber 221 a after flowing through the flow path 32, and is dischargedfrom the gas outlet port 27. The blood B flowing through the blood flowpaths 33 comes into contact with the surface of each of the hollow fibermembranes 31 of the oxygenator portion 10A, and gas exchange, that is,addition of oxygen and decarbonation are performed between the blood andthe gas G flowing through the flow paths 32.

Ina case where air bubbles mixed with the blood B which has beensubjected to gas exchange, these air bubbles are captured by the filtermember 41A and are prevented from flowing out to the downstream side ofthe filter member 41A.

The blood B which has been subjected to the heat exchange and the gasexchange as described above in order and from which air bubbles areremoved flows out of the blood outlet port 28.

As described above, all the hollow fiber membrane layers 3A and 3B areconstituted of a plurality of hollow fiber membranes 31. The hollowfiber membrane layer 3A and the hollow fiber membrane layer 3B have thesame hollow fiber membranes 31 even though the application of the hollowfiber membrane layer 3A and the hollow fiber membrane layer 3B aredifferent from each other, and therefore, the hollow fiber membranelayer 3A will be representatively described below.

The inner diameters ϕd₁ of the hollow fiber membranes 31 are preferably50 μm or larger and 700 μm or smaller and more preferably 70 μm orlarger and 600 μm or smaller (refer to FIG. 6). The outer diameters ϕD₂of the hollow fiber membranes 31 are preferably 100 μm or larger and1000 μm or smaller and more preferably 120 μm or larger and 800 μm orsmaller (refer to FIG. 6). Furthermore, the ratio d₁/d₂ of the innerdiameter ϕd₁ to the outer diameter ϕd₂ is preferably 0.5 or more and 0.9or less and more preferably 0.6 or more and 0.8 or less. In each of thehollow fiber membranes 31 having such conditions, it is possible tocomparatively reduce the pressure loss when the gas G is made to flow inthe flow paths 32 which are hollow portions of the hollow fibermembranes 31 while maintaining its strength, and such conditions alsocontribute to maintaining the winding state of the hollow fibermembranes 31. For example, when the inner diameter ϕd₁ is larger thanthe upper limit value, the thickness of the hollow fiber membranes 31becomes thin, and the strength of the hollow fiber membranes decreasesin accordance with other conditions. In addition, when the innerdiameter ϕd₁ is smaller than the lower limit value, the pressure losswhen the gas G is made to flow in the hollow fiber membranes 31increases in accordance with other conditions.

In addition, the distance between adjacent hollow fiber membranes 31 ismore preferably 1/10 or more and 1/1 or less of the ϕd₂.

The method for manufacturing such hollow fiber membranes 31 is notparticularly limited, but examples thereof include a method usingextrusion molding, and in addition, a method using a stretching methodor a solid-liquid phase separation method. It is possible to manufacturethe hollow fiber membranes 31 having a predetermined inner diameter 4d1and a predetermined outer diameter ϕD₂ through this method.

For example, as the constituent material of each of the hollow fibermembranes 31, hydrophobic polymer materials such as polypropylene,polyethylene, polysulfone, polyacrylonitrile, polytetrafluoroethylene,and polymethylpentene are used, a polyolefin resin is preferably used,and polypropylene is more preferably used. The selection of such resinmaterials contributes to maintaining the winding state of the hollowfiber membranes 31 and also to cost reduction during the manufacture ofthe hollow fiber membranes.

The hollow fiber membrane layer 3A is manufactured by winding such aplurality of hollow fiber membranes 31 around a columnar core asfollows.

As shown in FIGS. 7A, 7B, 8A, and 8B, a hollow fiber membrane 31 isreciprocated in a central axis O direction while being wound around acentral axis O of the first cylindrical member 241 (cylindrical body).At this time, the hollow fiber membrane 31 starts winding from a leftside starting point 311 of the central axis O direction and goes to theright side. On the right side, the hollow fiber membrane 31 is foldedback at a folding point (folded-back portion) 312. Thereafter, thehollow fiber membrane 31 returns to the left side again and reaches anending point 313. For example, in the winding state shown in FIG. 7, thehollow fiber membrane 31 is wound in the order of arrows i→ii→iii→iv→v.Then, during one reciprocation, as shown in FIG. 7A and 7B, the hollowfiber membrane 31 is wound at a predetermined number of turns N. In thewinding state shown in FIG. 7A and 7B, N=1, and the hollow fibermembrane 31 makes one around the central axis O while making onereciprocation. In addition, in the winding state shown in FIG. 8A and8B, the hollow fiber membrane 31 is wound in the order of arrowsi→ii→iii→iv→vi→vii. Then, during one reciprocation, as shown in FIG. 8Aand 8B, the hollow fiber membrane 31 makes two turns around the centralaxis O.

Thus, the hollow fiber membrane layer 3A comprises the hollow fibermembranes 31 inclined with respect to the central axis and wound aroundthe central axis.

As shown in FIG. 9, the hollow fiber membrane 31 comprises a heatconductive layer 5, a barrier layer 6, and an adhesion layer 7 as anexample of a layered structure thereof, and these are laminated frominside to outside in this order.

The heat conductive layer 5 has a thermal conductivity higher than thatof the adhesion layer 7 and the barrier layer 6, and is responsible forenhancing the thermal conductivity of the hollow fiber membranes 31.

The thermal conductivity of the heat conductive layer 5 at 20° C. ispreferably 0.3 W/m·K or higher and 0.6 W/m·K or lower, and morepreferably 0.4 W/m·K or higher and 0.6 W/m·K or lower. Accordingly, theabove-described effects can be more reliably exhibited.

The material of such a heat conductive layer 5 is not particularlylimited as long as it exhibits the above-described effects. For example,at least one selected from the group including polyolefin, polyamidesuch as nylon 66, polyurethane, polyester such as polyethyleneterephthalate, polybutylene terephthalate, and polycyclohexaneterephthalate, and a fluorine-based resin such aspolytetrafluoroethylene and ethylene-tetrafluoroethylene copolymer canbe used. Among these, high density polyethylene is preferably used.Accordingly, the above-described effects can be reliably exhibited.

The thickness T₅ of the heat conductive layer 5 is preferably 10 μm ormore and 60 μm or lower, and more preferably 20 μm or more and 50 μm orlower. Accordingly, the thermal conductivity of the hollow fibermembranes 31 can be sufficiently enhanced.

The adhesion layer 7 is a layer that can be positioned at the outermostlayer of hollow fiber membrane 31. This adhesion layer 7 has a portionthat can be in contact with the partition walls 8 and 9, and is fixed bythe partition walls 8 and 9.

Here, from the viewpoint of preventing the hollow fiber membrane layer3B (the same applies to hollow fiber membrane layer 3A) from beingseparated and departing from the partition walls 8 and 9, adhesion tothe partition walls 8 and 9 is required in a case where the hollow fibermembranes 31, particularly the adhesion layer 7 is positioned at theoutermost layer. In addition, as described above, the partition walls 8and 9 mainly contain polyurethane. That is, the adhesion layer 7 isrequired to have high adhesion with respect to polyurethane.

Particularly, in the case of using an olefin-based resin such as highdensity polyethylene for a heat conductive layer, since the olefin-basedresin has poor adhesion to other resins, it is necessary to improve theadhesion by providing an adhesion layer between the resin andpolyurethane. Thereby, in the present invention, the adhesion layer 7mainly contains a modified polyolefin resin. Accordingly, it is possibleto enhance the adhesion between the adhesion layer 7 and the partitionwalls 8 and 9, and prevent the hollow fiber membrane layers 3A and 3Bfrom being unintentionally separated from the partition walls 8 and 9.

In addition, the polyolefin-based resin is preferably a modifiedpolyolefin resin and more preferably modified polyethylene. Examples ofmodified polyethylene include acrylic modified polyethylene, siliconmodified polyethylene, and maleic anhydride modified polyethylene.Accordingly, the adhesion between the adhesion layer 7 and the partitionwalls 8 and 9 can be further enhanced.

The thickness T7 of the adhesion layer 7 is preferably 3 μm or more and40 μm or lower, and more preferably 10 μm or more and 30 μm or lower.Accordingly, the above-described effects can be more reliably exhibited.

The barrier layer 6 has a barrier property to hydrogen peroxide.Accordingly, it is possible to prevent the increase in the concentrationof hydrogen peroxide in the blood due to the hollow fiber membranes 31permeating hydrogen peroxide in the hydrogen peroxide solution.

In addition, the barrier layer 6 preferably has an oxygen permeabilitycoefficient at 25° C. of 0.1 cc·cm/m²·24 h/atm or more and 6 cc·cm/m²·24h/atm or less, and more preferably 0.5 cc·cm/m²·24 h/atm or more and 3.8cc·cm/m²24 h/atm or less. This makes it possible to more reliablyprevent the hollow fiber membrane 31 from permeating hydrogen peroxide.Note that, since the oxygen permeability coefficient and the hydrogenperoxide permeation amount have a correlation under predeterminedconditions, it is known that the permeation of hydrogen peroxide can beprevented by defining the oxygen permeability coefficient.

The barrier layer 6 is mainly made of a crystalline resin material. Inthe present specification, “crystalline resin material” refers to aresin having a high ratio of the amount of crystalline regions in whichmolecular chains are regularly arranged. Examples thereof includepolyethylene (PE), polypropylene (PP), polyamide (PA), polyacetal (POM),polybutylene terephthalate (PBT), polyethylene terephthalate (PET),syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), polyetherether ketone (PEEK), liquid crystal polymer (LCP), polyether nitrile(PEN), and ethylene-vinyl alcohol copolymer (EVOH), and among these,aliphatic polyamide is preferably used.

When the number of carbon atoms of the amide group contained in thealiphatic polyamide molecule is N and the number of carbon atoms of themethylene group contained therein is n, n/N of the aliphatic polyamideis preferably 9 or more, and for example, at least one of polyamide 11,polyamide 12, polyamide 10-10, and polyamide 10-12 is preferably used.Accordingly, the hydrogen peroxide permeation amount can be madesufficiently low. On the other hand, in a case where at least one ofpolyamide 11, polyamide 12, polyamide 6, and polyamide 66 is used, theoxygen permeability coefficient can be made sufficiently low. Inaddition, by using aliphatic polyamide in which n/N is 9 or more, thewater absorption rate of the barrier layer 6 can be made 2% or lower.Accordingly, high hydrophobicity can be exhibited with respect to a heatmedium containing hydrogen peroxide solution. Since hydrogen peroxidehas a relatively high affinity with respect to water, hydrogen peroxideeasily permeates if the water absorption rate is relatively high, but bysetting the water absorption rate of the barrier layer 6 to be 2% orless, excessive permeation of hydrogen peroxide can be prevented.

In addition, the thickness T₆ of the barrier layer 6 is preferably 1 μmor more and 60 μm or less, and more preferably 10 μm or more and 30 μmor less. When the barrier layer 6 is too thin, the hydrogen peroxidepermeation amount tends to be high. When the barrier layer 6 is toothick, the outer diameter of the hollow fiber membrane 31 tends toincrease in the case where the inner diameter of the hollow fibermembrane 31 is sufficiently ensured, and as a result, the blood fillingamount may be increased and the burden on the user may be increased.

Second Embodiment

FIG. 10 is a plane view showing a hollow fiber membrane sheet beforebecoming a hollow fiber membrane layer of a heat exchanger (secondembodiment) of the present invention. FIG. 11 is a perspective view of ahollow fiber membrane layer formed by folding the hollow fiber membranesheet shown in FIG. 10.

Hereinafter, a second embodiment of a heat exchanger of the presentinvention will be described while referring to the drawings. However,the difference from the above-described embodiment will be mainlydescribed and the description of the same matter will not be repeated.The present embodiment is the same as the first embodiment except thatthe configuration of the hollow fiber membrane layer is different fromthat in the first embodiment.

A hollow fiber membrane layer 3C in the oxygenator 10 of the presentembodiment is constituted of a hollow fiber membrane sheet 300 shown inFIG. 11.

The hollow fiber membrane sheet 300 is a sheet which has warp strings 31a composed of the plurality of hollow fiber membranes 31 and weftstrings 31 b composed of the plurality of hollow fiber membranes 31, inwhich the warp strings and the weft strings are braided.

As shown in FIG. 11, the hollow fiber membrane sheet 300 is alternatelyfolded in the surface direction to form the hollow fiber membrane layer3C having a prismatic outer shape.

The same effects as that of the first embodiment can be also obtained bysuch a hollow fiber membrane layer 3C.

Third Embodiment

FIG. 12 is a perspective view of a hollow fiber membrane layer providedin a heat exchanger (third embodiment) of the present invention.

Hereinafter, a third embodiment of a heat exchanger of the presentinvention will be described while referring to the drawing. However, thedifference from the above-described embodiment will be mainly describedand the description of the same matter will not be repeated. The presentembodiment is the same as the first embodiment except that theconfiguration of the hollow fiber membrane layer is different from thatin the first embodiment.

As shown in FIG. 12, a hollow fiber membrane layer 3D is molded into acylindrical shape by winding the hollow fiber membrane sheet 300 shownin FIG. 11 in a roll shape a plurality of times.

The same effects as the first embodiment and the second embodiment canalso be achieved with such a present embodiment.

Although the heat exchanger and the oxygenator of the present inventionhave been described above with reference to the illustrated embodiments,the present invention is not limited thereto.

In addition, each of the hollow fiber membranes constituting the hollowfiber membrane layer of the oxygenator portion and each of the hollowfiber membranes constituting the hollow fiber membrane layer of the heatexchange portion were the same as each other in the embodiments, but thepresent invention is not limited thereto. For example, one (former)hollow fiber membrane side may be thinner than the other (latter) hollowfiber membrane side, or both hollow fiber membrane sides may be formedof materials different from each other.

In addition, in the oxygenator portion and the heat exchange portion,the heat exchange portion is disposed inside and the oxygenator portionis disposed outside in the embodiments. However, the present inventionis not limited thereto, and the oxygenator portion may be disposedinside and the heat exchange portion may be disposed outside. In thiscase, blood flows down from the outside to the inside.

The heat exchanger of the present invention comprises a hollow fibermembrane layer which has a plurality of hollow fiber membranes and inwhich the plurality of hollow fiber membranes are laminated, and afixing portion which fixes both end portions of the hollow fibermembranes from outsides of the hollow fiber membranes. The fixingportion mainly contains polyurethane, and each of the hollow fibermembranes has a heat conductive layer containing high densitypolyethylene, and an adhesion layer provided on an outside of the heatconductive layer, bonded to the fixing portion, and mainly containing amodified polyolefin resin. Accordingly, the adhesion of the adhesionlayer positioned at the outermost layer of the hollow fiber membranesand the fixing portion can be enhanced. Accordingly, it is possible toprevent the hollow fiber membrane layer from being separated from thefixing portion, and to prevent the heat medium (water or hot water)passing through the inside of each of the hollow fiber membranes fromflowing out to the outside of the hollow fiber membranes and being mixedinto the patient's blood.

What is claimed is:
 1. A heat exchanger for a blood circulation circuit,comprising: a hollow fiber membrane layer having a plurality of hollowfiber membranes; and a fixing portion fixing both end portions of thehollow fiber membranes from outside of the hollow fiber membranes;wherein the fixing portion is comprised of polyurethane; and whereineach of the hollow fiber membranes has a heat conductive layercontaining high density polyethylene, and an adhesion layer provided onan outside of the heat conductive layer, bonded to the fixing portion,and comprising a modified polyolefin resin.
 2. The heat exchangeraccording to claim 1, each of the hollow fiber membranes furthercomprising: a barrier layer provided on the outside of the heatconductive layer and on an inside of the adhesion layer, wherein thebarrier layer is comprised of a material which is not permeable withrespect to hydrogen peroxide.
 3. The heat exchanger according to claim 1wherein the adhesion layer is comprised of modified polyethylene.
 4. Theheat exchanger according to claim 1 wherein the barrier layer iscomprised of a crystalline resin material.
 5. The heat exchangeraccording to claim 1 wherein the heat conductive layer has a thermalconductivity of 0.3 W/m·K or higher and 0.6 W/m·K or lower.
 6. The heatexchanger according to claim 1 wherein the hollow fiber membrane has anouter diameter of 1 mm or less.
 7. The heat exchanger according to claim1 wherein the hollow fiber membrane layer has a shape of a cylindricalbody and has the hollow fiber membranes wound around a central axis ofthe cylindrical body and inclined with respect to the central axis ofthe cylindrical body.
 8. The heat exchanger according to claim 1 whereinthe hollow fiber membrane layer has a shape of a cylindrical body, andhas warp strings in which the hollow fiber membranes are disposed alonga central axis of the cylindrical body and weft strings in which thehollow fiber membranes are disposed in a direction intersecting with thecentral axis of the cylindrical body, and the warp strings and the weftstrings are braided.
 9. An oxygenator for a blood circulation circuit,comprising: a hollow fiber membrane layer having a plurality of hollowfiber membranes; and a fixing portion fixing both end portions of thehollow fiber membranes from outside of the hollow fiber membranes;wherein the fixing portion is comprised of polyurethane; and whereineach of the hollow fiber membranes has a heat conductive layercontaining high density polyethylene, and an adhesion layer provided onan outside of the heat conductive layer, bonded to the fixing portion,and comprising a modified polyolefin resin.
 10. The oxygenator accordingto claim 9, each of the hollow fiber membranes further comprising: abarrier layer provided on the outside of the heat conductive layer andon an inside of the adhesion layer, wherein the barrier layer iscomprised of a material which is not permeable with respect to hydrogenperoxide.
 11. The oxygenator according to claim 9 wherein the adhesionlayer is comprised of modified polyethylene.
 12. The oxygenatoraccording to claim 9 wherein the barrier layer is comprised of acrystalline resin material.
 13. The oxygenator according to claim 9wherein the heat conductive layer has a thermal conductivity of 0.3W/m·K or higher and 0.6 W/m·K or lower.
 14. The oxygenator according toclaim 9 wherein the hollow fiber membrane has an outer diameter of 1 mmor less.
 15. The oxygenator according to claim 9 wherein the hollowfiber membrane layer has a shape of a cylindrical body and has thehollow fiber membranes wound around a central axis of the cylindricalbody and inclined with respect to the central axis of the cylindricalbody.
 16. The oxygenator according to claim 9 wherein the hollow fibermembrane layer has a shape of a cylindrical body, and has warp stringsin which the hollow fiber membranes are disposed along a central axis ofthe cylindrical body and weft strings in which the hollow fibermembranes are disposed in a direction intersecting with the central axisof the cylindrical body, and the warp strings and the weft strings arebraided.